Re: Reminder: Video Ingest over QUIC Side Meeting Friday 7/30 18:00 UTC

[Roland Zink <[e-mail]>]

Hi David,


In mobile networks the L2 transport block vary in size and can contain 
only a small fraction of an IP packet or several 1500 bytes packets. 
When filling the transport block you may have the chance to pack in the 
beginning of the next arrived packet or a complete but smaller IP 
packet. When the transport block can't be successfully transferred but 
the next one is then this may create a sort of HoL blocking, e.g. the 
remaining of the incomplete IP packet can't be forwarded until the 
transport block is retransmitted.


Regards,

Roland


Am 7/28/2021 um 11:15 PM schrieb David Schinazi:
> Why would we need a signal here? This applies to all traffic, be it 
> TCP QUIC or anything else. Firmwares introducing latency to reorder 
> packets was a reaction to bad implementations of TCP from a long time 
> ago that have been fixed in systems that care about performance. In 
> today's world, L2 is better off delivering any and all packets in the 
> order they arrive instead of introducing buffer bloat.
>
> David
>
> On Wed, Jul 28, 2021 at 1:24 PM Roberto Peon 
> <fenix=[e-mail] <mailto:[e-mail]>> wrote:
>
>     The ideal would be to have public bits that were intended to be
>     interpreted by (as you say, visible to) those layers so any L2
>     could adapted appropriately without reinventing the wheel.
>     It isn’t just the local radio firmware that one needs to worry
>     about—it is also the basestation(s) that may be “helping”.
>
>     Separately, but also important, is being able to get signals from
>     the application about what tradeoffs should be at the network. I
>     believe that this dovetails into many of the multipath issues, btw.
>
>     A couple potentially interesting params are:
>
>       A bit to say please don’t HoL block
>       Some kind of mechanism(s) to bound retries (e.g. “don’t retry
>     bit”, but that is obviously not as expressive as throw out packet
>     older than X microseconds)
>
>
>     -=R
>
>     *From: *QUIC <[e-mail]
>     <mailto:[e-mail]>> on behalf of Ian Swett
>     <ianswett=[e-mail]
>     <mailto:[e-mail]>>
>     *Date: *Wednesday, July 28, 2021 at 12:42 PM
>     *To: *"Das, Dibakar" <[e-mail]
>     <mailto:[e-mail]>>
>     *Cc: *Alan Frindell <afrind=[e-mail]
>     <mailto:[e-mail]>>, "[e-mail]
>     <mailto:[e-mail]>" <[e-mail] <mailto:[e-mail]>>,
>     "[e-mail] <mailto:[e-mail]>" <[e-mail]
>     <mailto:[e-mail]>>, Kirill Pugin <[e-mail]
>     <mailto:[e-mail]>>
>     *Subject: *Re: Reminder: Video Ingest over QUIC Side Meeting
>     Friday 7/30 18:00 UTC
>
>     Hi,
>
>     I can't answer for Alan, but my belief is yes.  Client wifi stacks
>     sometimes also do some reordering(and introduce the corresponding
>     latency), so if we could design an indication that in-order
>     delivery has no value, it could be fairly widely applicable.
>
>     That being said, I don't know what the right mechanism is? 
>     Would we need something visible to a network or can we get away
>     with a socket option that propagates to the local 5G network or
>     Wifi firmware when possible?
>
>     Ian
>
>     On Wed, Jul 28, 2021 at 3:15 PM Das, Dibakar
>     <[e-mail] <mailto:[e-mail]>> wrote:
>
>         Hi Kirill, Alan,
>
>         I could not attend the call this week and wont be able to
>         attend this side meeting either.
>
>         But I had a general question about the performance of all such
>         QUIC based protocols over wireless. Typically, the 5G and WiFI
>         MAC layers deliver frames in-order which sort of recreates the
>         HOL blocking problem at lower layers. I would expect this to
>         in turn prevent the QUIC protocol to achieve its full
>         performance gains at least in some congested network
>         scenarios. Considering that in-order delivery is made optional
>         in 5G PDCP, I was wondering if there could be a value to have
>         some signaling defined in the QUIC (or RUSH ?) protocol that
>         would allow lower layers to make better decision about whether
>         to enable/disable in-order delivery for certain streams.
>
>         I apologize in advance if this is not the right venue to ask
>         questions.
>
>         Regards,
>
>         Dibakar
>
>         *From:* QUIC <[e-mail]
>         <mailto:[e-mail]>> *On Behalf Of *Alan Frindell
>         *Sent:* Wednesday, July 28, 2021 8:42 AM
>         *To:* [e-mail] <mailto:[e-mail]>; [e-mail]
>         <mailto:[e-mail]>; QUIC WG <[e-mail]
>         <mailto:[e-mail]>>; [e-mail] <mailto:[e-mail]>
>         *Cc:* Kirill Pugin <[e-mail] <mailto:[e-mail]>>
>         *Subject:* Reminder: Video Ingest over QUIC Side Meeting
>         Friday 7/30 18:00 UTC
>
>         Video Ingest over QUIC Side Meeting Friday 7/30 18:00 UTC / 11
>         Pacific
>
>         Link to draft agenda and video conference details:
>         https://github.com/afrind/draft-rush/blob/main/meeting-materials/agenda.2021.07.03.md
>         <https://github.com/afrind/draft-rush/blob/main/meeting-materials/agenda.2021.07.03.md>
>
>         -Alan
>